Genetic Variant SMAD4:p.Thr349Ile (chr18-51065513-C-T) – ACMG Classification: Likely_benign (-1 pts)

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 4P and 5B. PM1PP3_ModerateBS1_SupportingBS2

The NM_005359.6(SMAD4):c.1046C>T(p.Thr349Ile) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000167 in 1,613,934 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T349A) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000018 ( 0 hom. )

Consequence

SMAD4
NM_005359.6 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:7B:1

Conservation

PhyloP100: 7.76

Publications

4 publications found

Variant links:

Genes affected

SMAD4 (HGNC:6770): (SMAD family member 4) This gene encodes a member of the Smad family of signal transduction proteins. Smad proteins are phosphorylated and activated by transmembrane serine-threonine receptor kinases in response to transforming growth factor (TGF)-beta signaling. The product of this gene forms homomeric complexes and heteromeric complexes with other activated Smad proteins, which then accumulate in the nucleus and regulate the transcription of target genes. This protein binds to DNA and recognizes an 8-bp palindromic sequence (GTCTAGAC) called the Smad-binding element (SBE). The protein acts as a tumor suppressor and inhibits epithelial cell proliferation. It may also have an inhibitory effect on tumors by reducing angiogenesis and increasing blood vessel hyperpermeability. The encoded protein is a crucial component of the bone morphogenetic protein signaling pathway. The Smad proteins are subject to complex regulation by post-translational modifications. Mutations or deletions in this gene have been shown to result in pancreatic cancer, juvenile polyposis syndrome, and hereditary hemorrhagic telangiectasia syndrome. [provided by RefSeq, May 2022]

SMAD4 Gene-Disease associations (from GenCC):

juvenile polyposis/hereditary hemorrhagic telangiectasia syndrome
Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: ClinGen, PanelApp Australia, Labcorp Genetics (formerly Invitae), G2P, Genomics England PanelApp
Myhre syndrome
Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), ClinGen, PanelApp Australia, G2P, Orphanet
generalized juvenile polyposis/juvenile polyposis coli
Inheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Orphanet
juvenile polyposis syndrome
Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
familial thoracic aortic aneurysm and aortic dissection
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
hereditary hemorrhagic telangiectasia
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
pulmonary arterial hypertension
Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

SMAD4 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -1 ACMG points.

PM1

In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 24 uncertain in NM_005359.6

PP3

MetaRNN computational evidence supports a deleterious effect, 0.903

BS1

Variant frequency is greater than expected in population nfe. GnomAdExome4 allele frequency = 0.0000178 (26/1461720) while in subpopulation NFE AF = 0.0000234 (26/1111880). AF 95% confidence interval is 0.0000163. There are 0 homozygotes in GnomAdExome4. There are 10 alleles in the male GnomAdExome4 subpopulation. Median coverage is 31. This position passed quality control check. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

BS2

High AC in GnomAdExome4 at 26 AD gene.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_005359.6. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
SMAD4	NM_005359.6	MANE Select	c.1046C>T	p.Thr349Ile	missense	Exon 9 of 12	NP_005350.1	Q13485
SMAD4	NM_001407041.1		c.1046C>T	p.Thr349Ile	missense	Exon 9 of 12	NP_001393970.1	A0A024R274
SMAD4	NM_001407042.1		c.1046C>T	p.Thr349Ile	missense	Exon 9 of 12	NP_001393971.1	Q13485

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
SMAD4	ENST00000342988.8	TSL:5 MANE Select	c.1046C>T	p.Thr349Ile	missense	Exon 9 of 12	ENSP00000341551.3	Q13485
SMAD4	ENST00000591126.5	TSL:1	n.3047C>T		non_coding_transcript_exon	Exon 5 of 8
SMAD4	ENST00000714264.1		c.1127C>T	p.Thr376Ile	missense	Exon 9 of 12	ENSP00000519545.1	A0AAQ5BHY6

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152214

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000239

AC:

AN:

251444

AF XY:

0.00000736

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000528

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000178

AC:

AN:

1461720

Hom.:

Cov.:

AF XY:

0.0000138

AC XY:

AN XY:

727166

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33476

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26130

East Asian (EAS)

AF:

0.00

AC:

AN:

39688

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53418

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5766

European-Non Finnish (NFE)

AF:

0.0000234

AC:

AN:

1111880

Other (OTH)

AF:

0.00

AC:

AN:

60380

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.502

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152214

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74358

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41462

American (AMR)

AF:

0.00

AC:

AN:

15290

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3466

East Asian (EAS)

AF:

0.00

AC:

AN:

5200

South Asian (SAS)

AF:

0.00

AC:

AN:

4828

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10610

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000147

AC:

AN:

68038

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.525

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.0000529

Hom.:

Bravo

AF:

0.0000189

ExAC

AF:

0.00000824

AC:

ClinVar

ClinVar submissions

Significance:Conflicting classifications of pathogenicity

Revision:criteria provided, conflicting classifications

View on ClinVar

Pathogenic

VUS

Benign

Condition

Juvenile polyposis/hereditary hemorrhagic telangiectasia syndrome (3)

Juvenile polyposis syndrome (2)

Hereditary cancer-predisposing syndrome (1)

Hereditary cancer-predisposing syndrome;C4707243:Familial thoracic aortic aneurysm and aortic dissection (1)

not provided (1)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.37

BayesDel_addAF

Pathogenic

0.39

BayesDel_noAF

Pathogenic

0.48

CADD

Pathogenic

(source)

DANN

Uncertain

0.99

DEOGEN2

Pathogenic

0.98

Eigen

Uncertain

0.54

Eigen_PC

Uncertain

0.61

FATHMM_MKL

Pathogenic

0.98

LIST_S2

Uncertain

0.97

M_CAP

Pathogenic

0.35

MetaRNN

Pathogenic

0.90

MetaSVM

Pathogenic

0.88

MutationAssessor

Benign

1.3

PhyloP100

7.8

PrimateAI

Pathogenic

0.89

PROVEAN

Uncertain

-4.2

REVEL

Pathogenic

0.78

Sift

Benign

0.18

Sift4G

Benign

0.76

Polyphen

1.0

Vest4

0.96

MVP

0.97

MPC

1.1

ClinPred

0.83

GERP RS

5.9

Varity_R

0.57

gMVP

0.81

Mutation Taster

=10/90

disease causing

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.070

Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over